1. Field of the Invention
The present invention relates to an optical pickup device for irradiating laser light on a recording surface of an optical disk to perform recording and reproduction of information, and to a technology effective to be used in a disk drive which supports a plurality of types of optical disks.
2. Description of the Related Art
At present, a plurality of types of optical disks such as CDs (compact disk), DVDs (Digital Versatile Disk), or blue-violet laser optical disks having a capacity which is several times as much as the DVD have come into practical use. When performing recording or reproduction of information on the plurality of types of optical disks as such, it is necessary to employ laser light different in wavelength or objective lenses of different apertures depending on media type.
In the related art, there is a disk drive which supports a plurality of optical disks including optical pickups of two systems and moving mechanisms of two systems for moving the optical pickups of these two systems separately in the direction of the radius of the disk. However, in this configuration, there arises a problem in that the structure of the device as a whole is upsized, and a cost increases as well.
There is another technology disclosed in JP-A-2002-123969 as a technology in the related art which can support a plurality of optical disks with a single optical pickup. According to this technology, a single optical pickup includes two semiconductor lasers each emitting laser light of three wavelengths and the two objective lenses having different apertures, which are switched for use.
In the optical pickup, it is necessary to drive the objective lens, which opposes to the optical disk, in the focusing direction and the tracking direction, and perform servo-control so that laser light is not displaced from an objective data track. In the device disclosed in JP-A-2002-123969, a plurality of sets of light receiving surface groups are provided in an optical sensor so as to support the laser light of different wavelength respectively, the laser light of the respective wavelengths are detected on the light receiving surface groups corresponding to the respective wavelengths, and a focus error signal or a tracking error signal required for the above-described servo-control are generated based on the result of detection.
However, in the technology of JP-A-2002-123969, since the plurality of sets of light receiving surface groups are provided in the optical sensor so as to support the laser light of respective wavelengths, there arises a problem in that the cost of the optical sensor increases.